属性偏移辅助实现炮检距域共成像点道集计算

波动方程偏移的成像精度高于Kirchhoff类偏移，且对速度误差更敏感，故舍弃Kirchhoff深度偏移，针对波动方程炮检距域共成像点道集直接进行速度迭代，更具现实意义。为此提出一种基于属性偏移的计算策略，可实现高效的波动方程类偏移的炮检距域共成像点道集计算。通过对地表炮检距调制后的数据再偏移，将该偏移结果与原始数据偏移结果的比值作为各成像点的地表炮检距值；依此将偏移结果重排入所属炮检距段；逐炮依次计算并叠加，最终获得地表炮检距道集。上述两次偏移可纳入成像循环中同时计算，因此只增加了一次检波点波场的传播，计算量仅增加约30%。通过2D、3D模型及实际数据对比，验证了该计算方法的有效性。

Offset-domain common image gathers on wave equation assisted by attribute migration

Seismic migration based on wave equation is more accurate than Kirchhoff-based migration,and the former is more sensitive to the accuracy of a velocity model.Therefore,instead of Kirchhoff depth migration,it is of important practical significance for velocity iteration of offset-domain common image gathers based on wave equation.A computation scheme based on attribute migration is proposed to analyze offset-domain common image gathers through wave equation migration.In other words,migration is done after modulating surface offset,then the ratio of the migration based on modulated offset to the migration based on original data is taken as the surface offset of an imaging point.By giving new migration to its corresponding offset,and calculating and stacking literately,the final result is surface offset gathers.In practice,the two kinds of migration are performed during the same migration circle,and the computing effort is only increased by 30% since only increasing the propagation of receiver wavefield.2D and 3D model and field data have proved the method effective.